Various types of surface mountable microphone package architects have been used through the years. Within these assemblies, different electrical components are housed together forming an assembly. For example, a microphone assembly typically includes a Microelectromechanical system (MEMS) device or transducer, and an integrated circuit (IC). One example of a MEMS device includes a diaphragm and a back plate. The housing of the assembly typically contains a port or opening to allow acoustic energy to enter the microphone assembly. This acoustic energy, in turn, causes the diaphragm in the MEMS device to deflect. As the diaphragm deflects, the electrical potential between the back plate and the diaphragm varies and creates an electrical signal proportional to the acoustic energy acting on the diaphragm. The electrical signal is then routed to an external interface allowing the end user to make a mechanically and electrically robust connection.
The acoustic performance of a microphone assembly is related in part to the ratio of front volume (i.e., the volume of air between the diaphragm and the acoustic port) to back volume (i.e., the volume of the air contained by the package cavity and diaphragm) of the assembly. In typical top port devices, the components are attached directly to the substrate or base and the acoustic port is located on the top or lid, making the front volume large relative to the back volume. This is not the preferred ratio needed for optimum performance (i.e. high sensitivity, flat wideband response) of a microphone assembly.
All of the above-mentioned disadvantages with previous approaches have resulted in general user dissatisfaction with some aspects of these previous approaches.
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